In recent years, the standard of living in this country has caused a growing need for chemical compounds of all kinds, including toxic, flammable and otherwise hazardous and valuable pressurized gases and liquids. Transportation and storage of such chemicals has always been an important concern. Furthermore, safe, reliable transportation and storage of hazardous materials has become a highlight in recent years with the growth of environmental protection and awareness. Transportation tanks used on railroads, semitrailer trucks and modular containers for sea and land generally have inlet-outlet ports which are used to load and unload chemical cargo. These inlet-outlet ports are typically covered and closed by valves and other fixtures which protrude out from the surface of the vessel shell. Such protrusions are vulnerable to damage or rupture due to collisions, fire, vandalism or the like.
Many attempts have been made to protect these valve fixtures. One such example is that of a dome structure as placed over the valves or fixtures. While these dome structures help to streamline the vessel and protect the valve and access door assemblies, they still form abutments which can tear or be crushed during an accident.
Another example is the use of large recessed areas covered by a structural plate to deflect colliding objects. A group of portals and valves are placed at the bottom of the recess. These recesses are often so large that they can weaken the structural shell of the vessel. In addition, the recesses can be difficult to maintain because the recesses allow water to accumulate, possibly leading to corrosion of the vessel shell. Furthermore, the recessed valves make connections to the valve portals inconvenient because the operator must manipulate heavy wrenches while stretching outward and downward to connect and disconnect conduit to the portals for loading and unloading purposes.
Accordingly, there is a need for a reinforced vessel and valve assembly to protect a chemical cargo which can withstand the forces of an accident, fire, corrosion or vandalism and yet provide easy access to the valves and fixtures being protected. In addition, there is a need for an area within the vessel shell having a sufficient thickness to mount threaded valves and fixtures without weakening the vessel shell. The present invention provides such a device.